Quote:
Originally Posted by
iLikeItInTheEar 
Hi - Given that a lot of us use iPhones as our source, I was wondering if anyone's run tests comparing listening to an iPhone without an amp and again but with an amp...?
I'm awaiting delivery of my first portable amp and was wondering whether my iPhone will work less and save battery power by using an amp thereby bypassing the on board iPhone amp?
Best I understand about such devices is technically you do not bypass the amp, since the amp and DAC on mobile devices are a single chip. Basically, it's a DAC designed to output a signal that can drive earphones, including a digital potentiometer. Depending on the device some might have some kind of circuit after the DAC to allow for a lineout signal, but that's probably just the Classic. I wouldn't bet on a smartphone having such a circuit.
A more relevant device would be a portable DAC-Amp. You bypass the integrated chip, however you'd be using the other chips to stream audio out through its dock/usb, so the question is whether the integrated audio chip uses more power than the USB chip.
BTW some iDevice DACs (with an amp or not) might have a charging circuit on the input port like the HRT iStreamer, but the 12v versio is still too bulky to use on the go given the size of the battery pack it'll use.
